The agency thinks the new approach will result in more realistic ratings, especially for hybrids.

The Environmental Protection Agency is getting tired of discovering automakers overstating their vehicles' fuel economy figures, and it's apparently actually trying to do something about it. The government regulator has issued a new proposal that would force companies to conduct road tests to calculate their figures. The regulation isn't a guarantee yet, though, because it first has to go through a period of public comment.

According to The Wall Street Journal, the proposed rules come partially as a result of Ford, Hyundai and Kia re-stating the fuel economy results of select vehicles after finding their original ratings to be inaccurate. Under the regulation, automakers would be required to create their calculations for air resistance and rolling friction from real-world data gathered on a test track, rather than from computer models. Currently, EPA test procedures take place on dynamometers and involve professional drivers executing standardized tests designed to mimic typical city and highway drives.

The agency thinks that the new approach will result in more realistic ratings, especially for hybrids. "Some automakers already do this, but we are establishing a regulatory requirement for all automakers," said Chris Grundler, director of the EPA's Office of Transportation and Air Quality, to the WSJ.

The EPA wasn't happy about the change. "This issue highlights the need for continued strong oversight of the fuel economy labeling program," said a statement from Grundler after Ford's announcement. "Consumers need to trust that fuel economy window stickers are giving consumers reliable and fair estimates of real world fuel economy."

There may also be good news for the fuel economy ratings of diesel vehicles in the future. According to the WSJ, Grundler is also tasking engineers to find out why the EPA's tests tend to rate diesels lower than their real-world results.

Do you think real-world fuel economy road tests are a good idea, or will they just lead to more variation? Vote in our poll below, then have your say in Comments.

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Build a national test track that all manufacturers do their final mpg testing on. It doesn't have to be government owned, it could be owned and run by an independent private third party. Make the city and highway testing protocol universal across all manufacturers. This protocol would identify minimum speeds, distances, etc. so that every car essentially takes the same test. Sure, real world results would vary from these results, but at least all models would start from the same baseline.

Jim, it's already a standard protocol. And Consumer Reports already does exactly what you suggest. The problem is that automakers aren't following the protocol, and when discovered, have to change their ratings. This is about enforcement, not reinventing the wheel.

Just give the public accurate numbers and let the public make the decision. With today's system the number the public gets is wrong, so it's like automakers is lying and government is spending money for nothing as EPA number is meaningless.

I'd say yes but there is no way real world testing is going to be equal for all cars and tests, the same way sometimes you need 10 minutes to get to work, sometimes it's 15. If some mean average testing procedure could be produced (like mileage calculated out of 10 tests in 10 different days but with a given range of meteorological conditions), it could work, but that's no easy or cheap task.

I've found that the EPA estimates are pretty accurate for the cars I have owned. Gas mileage is going to vary considerably based on how you drive. Maybe they should give an estimated gas mileage range, like 22 - 26 mpg in the city.

So, when you drive on the highway, you get into your car and are immediately transported onto the roadway at 65+mph then? There's no driving to the highway, accelerating, merging, passing, slowing down, nothing? Just all straight 65+mph driving huh? If you took a look at your average speed of your daily commute, I bet you'd be quite surprised at how low that figure actually is, even if much of your time is spent at highway speeds. Don't be confused by the average speed they use, it's simply that, an average.

I don't think people who use FUELLY are a good representation of fuel economy for each car. Chances are that if you're a FUELLY member, you're more economical in your driving style and probably implement some fuel saving measures that most have no idea about.

Actually, you ought to read what is on your screen before YOU post. I didnt say the EPA should use fuelly, I said I as in ME, use data from fuelly to see real world data. Which would suggest, idiot, that I wouldnt purchase the car the day it hits showroom floors, it obviously has been on sale long enough for owners to drive the vehicles, make accounts, and record fuel data. Again, read what is on your screen and stop making something out of things that arent there, again, idiot.